Voltage change-over relay



Aug. 5, 1941. A, a NEW-5N 2,251,494

VOLTAGE CHANGE-OVER RELAY I Filed D60. 31, 1938 2 Sheets-Sheet l u su s' Alwin Ba Newlom Clfforngg me@ M' All@ 5, 1941- v A. B. NwToN 2,251,494

VOLTAGE CHANGE-OVER RLAY Filed Dec. 3l, 1958 2 Sheets-Sheet 2 Gttorngg Patented Aug. 5, 1941 2,251,494 VOLTAGE CHANGE-OVER RELAY Alwin B. Newton,

Minneapolis-Honeywell Minneapolis, Minn., a corporation of Delaware Application December 31, 1938, Serial No. 248,912

19 Claims.

My invention relates to electrical equipment particularly relays and control systems embodying-relays.

Electrical equipment is ordinarily designed and built for use at stated direct current voltages or at stated alternating current voltages and frequencies. In different localities available power sources are often only alternating current or drect current or alternating current of a 4frequency which may vary from the more commonly found frequency of 60 cycles. Hence ordinarily electrical equipment is far from able to use in all parts of the country and articles of electrical manufacture for national distribution must usually be specially constructed for diiferent localities depending upon the nature of the source of power encountered. Having particular reference to` electrical relays, which often form integral parts of such articles of manufacture as control instruments, devices, and systems, in order to supply such articles of manufacture to a national market, development and production costs are relatively heavy due to the necessity of having a number o different items of each type to accommodate the various different power sources to be used.

Broadly, the object of my invention is to render electrical equipment, particularly relays, more universally adaptable to different sources of electric power.

Another object is to provide means for conveniently changing over a relay so as to adapt it to use with different kinds and sources of power.

Another object is to provide a control rsystemembodying a relay having means adapting it to use at different voltages and frequencies, and a pilot relay cooperating in a manner whereby the voltage impressed on the pilot relay remains the same even though voltage of the power source for the system is changed.

Another object is the provision of a relay having a plurality of coils and means for connecting the coils in different relationships depending upon the nature of the power supply.

Another object is the provision in .electrical apparatus of a plurality of coils having taps connected to electrical-contacts, in combination with a removable unit having contacts for engaging the aforesaid contacts, the unit having means connecting its contacts so as to connect the coils according to a certain relationship when the unit is in place.

Another object is the provision oi a relay having a plurality of coils having taps connected to electrical contacts and a removable invertible being universally adapt- Minneapolis, Minn., assigner to Regulator Company,

unit having contacts on both sides for engaging the aforesaid contacts, the unit having wiring connecting its contacts so `as to connect the coils according to a certain relationship when the unit is in place with its contacts on one side engaging the first mentioned contacts and to connect the coils according to another relationship when it is in place in its inverted position.

Another object is the provision of a relay and unit as stated in the previous object wherein the unit embodies resistances which are connected in circuit with the coils according to certain ing a plurality of coils having relationships depending on the position oi the unit.

.Another object is the provision of a relay havtaps connected to electrical contacts and a removable unit having contacts for engaging the aforesaid contacts, the

unit embodying a resistance, movable contacts,

' means whereby the relay can operate the ymovable contacts, and wiring such that the coils are connected according to a certain relationship when the unit is in place and ,whereby operation of the movable contacts by the relay places the resistance in series with one or more coils. [A

Another object is the provision of a-relay and unit as stated in the previous object, the unit being constructed so that it can be placed in an inverted position with the movable contacts being actuable by the relay in the same manner. A more complete knowledge of my invention enabling those skilled in the art to make, compound, and use the same may be gained from the accompanying drawings tion. I

Figure l is a partly diagrammatic view of my improved relay showing the voltage change-over structure in cross section, the relay being shown in combination with an automatic electrical control system including a pilot relay,

Figure 2 is a view o f a detail portion of the relay of Figure 1 and another view in inverted position of that .portion of the voltage changeover equipment which. will be referred to as the adaptor unit,

Figure 3 represents a slightly modified form of the relay shown in combination with another form of adaptor unit,

Figure 4 represents another slightly modified form of the relay shown in combination-with another form of adaptor unit, and

Figure 51s a detail view of a portion of the relay of Figure 3 shown in combination with another form of adaptor unit. Referring to Figure 1 of the drawings, numeral and detailed specifica- I designates generally one form which my improved relay may take. The relay comprises a l base or panel II which forms a support for the various elements comprising the relay. Numeral I2 indicates a core member which is of substantially a horizontal U-shape, the joined portions of the legs of the U being attached to the support II in any suitable manner. The core I2 is made of magnetic material and may be of laminated or other suitable construction, the lower leg of the core having a pontion I3 forming a bracket to which is pivoted or hinged an armature generally designated at I4. The armature comprises a member I5 made of soft iron or other suitable magnetic material through which a pivot pin I6 extends and to which is attached an angular bracket member I1 which is preferably made of Bakelite or other suitabl'finsulative material, the member I1 being attached to member I5 by a screw I8. Encircling the upper end of the member I5 is a brass band 2I which serves as an antistick element to prevent the relay remaining in position when it has been deenergized. The brass band 2I tends to inhibit the passage of magnetic flux between the core I2 and the member I5, this effect of the band 2I being sufficient to prevent any residual magnetism remaining in core I2 after it has been deenergized 'from causing the armature to remain in its energized position. The brass band 2| is more important when the relay is used with direct current power because with alternating 'current power the alternating flux may be at or near a zero value at the time the relay is ldeenergized so that the amount of residual magnetism would be more or less inappreciable. The screw I8 serves to attach a contact strip 22 to the member I1 and also a metal backing strip 23 for the contact strip 22 and a metal member 24 on the opposite side of the contact strip 22. The contact strip 22 carries a contact 25 which is cooperable with a xed contact 26 supported on a contact bracket 21 attached to the support or panel II. Contacts 25 and 26 are brought together when the armature is rotated in a counter-clockwise direction and the purpose of the metal member 24 is to positively move the contact strip 22 in a direction to separate contacts 25 and 26 when the armature is rotated'in a clockwise direction. It is conceivable that contacts 25 and 26 might become burned and tend to stick and inasmuch as the contact strip 22 is exible the more rigid member 24 is necessary to positively insure separation of the contacts when the armature is otherwise free to rotate clockwise. strip 28 having a contact 29 at its extremity cooperable with a xed Contact 30 supported by a bracket 3I attached to the support or panel II. Adjacent the contact strip 28 is a metal member 32 which serves the same purpose as the pre- The member I1 also 'carries contact.

made of a plastic composition or material. The

block 31 is recessed as shown, the bottom of the recess forming a flat surface in which are imbedded four contact strips or bars 38, 39, 40, and 4I, the Contact surfaces of the contact strips rising out of the adjacent surface of the plastic material. Between the contact strips 39 and 40 is a small recess 42 in the material of the block 31. Midway between the contact strips 38 and 39 is a screw threaded opening 43 adapted to receive a screw and midway between the contact strips 40 and 4I is a corresponding opening 44. Also inidway between the contact strips 39 and 40 there is another-similar screw threaded opening 45 at the bottom of the recess 42 (see Figure'2).

In my particular relay I employ two coil windingsl or a coil having two separate parts. On Figure l I have shown two coils indicated at 46 and 41 wound on the upper leg of the core I 2. The end terminals of these coils are tapped, there being wires 48 and 49 connecting the ends of coil 46 to Contact strips 38 and 40, respectively, and wires 50 and 5I connecting the ends of coil 41 to Contact strips 39 and 4I, respectively. As set forth earlier in my disclosure, my relay is intended to be used with power sources of different voltages and to make the change-over adaptation for use with one voltage or another I use the two coils and the structure being described for connecting them either in series or in parallel. I accomplish making series or parallel connections between the coils 46 and 41 by bridging certain of the contact strips 38 to 4I, inclusive. This may be done in various ways all within the scope and purview of my invention. It may be done by inserting screws in the openings 43, 44, or 45 so as to bridge the contact strips adjacent these openings or by means of an adaptor member or unit generally designated at 54.

Referring to Figure 2 this gure shows the block member 31 with the adaptor unit 54 shown spaced therefrom and in an inverted position. Figure 2 also shows in outline the position which the heads of suitable screws would take if screwed into the openings 43 and 44. From Figure 2 it is readily seen that the screw on the left in opening 43 would bridge contact strips 38 and 39 while the other screw would bridge contact strips 4l) and 4I. With screws in the position shown in outline of Figure 2 coils 46 and 41 would be connected in parallel while if only one screw were inserted in the opening 45 s'o as to bridge contact strips 39 and 40 the coils 46 and 41 would become connected in series. The series and parallel circuits produced by insertion ofthe screws in the manner described will be traced in the description of operation following.

The relay I0 and its various elements as so far described is suitably designed and constructed so that vit will function properly without excess heating when 220 volts alternating current is impressed thereon with coils 46 and 41 connected in series. If the power to be used is at volts alternating current the coils are thenvconnected in parallel as described and the relay will then also function properly without excess heating.

The alternating current frequency accompanying the 110 volts and 220 volts alternating current power sources referred to above which would be most commonly lfound would be 60 cycles. My relay is to be universally adaptable to other frequencies such as 25 or 40 cycles and to direct current supplies as Well. To adapt the relay to lower frequencies or to direct current it is necessary to connect resistance in series with the coils both when they y in series for 220 volt application and .when they are in parallel position as seen in Figure 2 a single screw as for 110 volt application. In other words, two shown in outline in the upper part of Figure 2 coils which are constructed to operate properly is used to retain the adaptor unit in position.` in series at 220 volts alternating current would The head of this screw then bridges contact strips overheat if 220 volts direct current were im- 5 59 and 6|) and connects the 'two coils 46 and 41 pressed on them while connected `in series. in series with each other and with the two re- Similarly two coils which function 'properly in sistances 68 and 69. This circuit will be traced parallel at 110 volts would overheat when 110 later in the description. volts direct current was impressed .on them un- The automatic control system of Figure 1 in 4 less additional resistance were connected in sewhich I have shown my improved relay emries with each coil. Frequencies lower than 60 bodied comprises a thermostat 14 of convencycles would also cause overheating of coils which tional type having a bimetal element 'and two operate properly at 60 cycles unless resistance flexible contact blades 16 and 11 movable thereis connected in circuit with the coils. To provide by. The blades 16 and 11 in this typeof therfor adapting the relayto various frequencies and 15 mostat are arranged to sequentially engage with to direct current power I employ the adaptor respective fixed electrical contacts 18 and 19. unit which I have designated by numeral 54. The blades 16 and 11 engage and disengage from Referring to Figure 1 this unit takes the form their respective contacts at temperatures between of a block which is preferably made of avplastic which there is a differential of 2` for example. composition or material molded so as' to jtake 20 Numeral 8|) designates' generally a pilot relay the general shape shown in cross section iri'Figcomprising a coil 8| arranged to move a pair of ure l. The unit 54 is shaped so that it will fit switch blades 82 and 83 to the left when the into the recess in the block 31 there being four n coil is energized, the blades 82 and 83 cooperatcontact strips 55, 56, 51, and 58 imbedded or ing with iixed electrical contacts 84 and 85, remounted in the material lof the unit 54 which are 25 spectively. Numeral 86 designates an overload similar to the contact strips 38 to 4| already cut-out which may be of conventional type indescribed and which are so arranged that they cluding a bimetal switch .element 81 carrying mate with and engage the latter contact strips a contact 88 cooperating with fixed contact 89. when the unit 54 is in the position shown in Fig- Adjacent the element 81 is an electrical heating ure 1. The opposite side of the unit 54, that is, 3o resistance 90 in the load circuit which extends the upper side as seen in Figure 1, is similarly through the contacts and 26. By way of shaped so that it will t into the recess in block example I have shown a motor 9| as the elec- 31 in the same manner, there being two contact trical load to be controlled it being apparent of strips 59 and 60 correspondingly imbedded in course that any other type of electrical loads this side of the unit 54. Between the contact 85' could be substituted. Numerals 92 and 93 desigstrips 59 and/60 is a projection 6| and an opennate line conductors which may be connected to ing 62 extends through the projection 6| and the source of external power which may be of the entire unit 54 so that a screw 63 may pass various natures as will now be dealt with. through the opening for retaining the unit 54 in While I have disclosed herein a temperature position as shown in Figure 1, the screw 5| 40 control systemy it will be understood that my rebeing screwed into the opening in the block lay may be embodied in various types of equp 41. The purpose of the projection 6| is to prement such as control instruments or devices or vent the head of the screw 63 from bridging the thev like and that such instruments or devices contact strips 59 and 60 when the unit 54- is in may be distributed for commercial or domestic the position shown in Figure l. Figure 2 shows 45 use in localities where the available electric power the unit 54 in inverted position and spaced from may be alternating current or direct current and the block 31. From Figures 1 and 2 it can be may be at various voltages and frequencies. Let seen that the unit 54 is substantially symmetriit be assumed that the line conductors 92 and cal` on opposite sides of a central horizontal 93 are connected to a source of 110 volt alternatplane.l When unit 54 is placed in the recess in 50 ing current power of 60 cycle frequency. Under block 31 with the unit inverted as seen in Figure these conditions the adaptor unit 54 will not be 2 the projection 6| extends into the small recess in use but two screws will `be in the block 31 42 in the block 31. The unit 54 may have laterally in the manner shown in outline in Figure 2. extending ear portions 66 and 61 and within the The thermostat 14 may be set so that blade 16 unit are embodied two electrical resistances 68 55 engages contact 18 at '12 and blade 11 engages and 69. The resistances 68 and 69 may be4 discontact 19 at 70 and when the temperature falls posed Within suitable openings in the material to or below '10 both blades will be in engagement of unit 54 or the material of the unit 54 may with their respective contacts. When this occurs be directly moulded around these resistances. a circuit will be completed for energizing the pilot The ends of resistance 68 are connected to con- G0 relay 80 as follows: from line conductor 93' to wire tact strips and 56, respectively, and the ends 94, wire 48, contact strip 38, the head of the screw of resistance 69 are connected to contact strips bridging contact strips 38 and 39, contact strip 51 and 58, respectively. Contact strip 55 is con- 39, wire 59, coil 46, wire 95 (which is connected nected to contact strip 59 by a suitable connecto the left end of coil 41) xed contact 18, thertion 10 while contact strip 58 is connected to mostat blade 16, thermostat blade 11, contact Contact strip by asuitable connection 1|. The 19, wire 96, coil 8|, Wire 91, OVPllOad Cut-011i connections 10 and 1| may be wires or metal 86, wire'98 backtoline conductor 93. Upon comconnections formed within the material of the` pletion of Vthis circuit and 'consequentenergizaunit 54 or externally thereof. tion of coil 8| switch blades 82 and 83 are moved With the adaptor unit 54 in the position shown 0 .to the left into engagement -with their respective in Figure 1 the coils 446 and 41 are connected in contacts. Upon engagement o f blade 62 with pe* allel with one of the resistances 68 and 69 1n contact 84 a maintaining circuit for coil 8| is series with each coil. These circuits will be produced which is independent of thermostat traced in the description of operation following. blade 11 and is as follows: from line conductor 1f theunit 54 is inserted into block 31 in inverted 75 93 to wire 94. wire 48Kcontact strip 38. the head of the screw bridging contact strips 38 and 39, contact strip 39, wire 50, coil 46, wire 95, contact 18, thermostat blade 16, element 15, wire 99, contact 84, blade 82, wire |02, coil 8|, wire 91, overload cut-out 86 and wire 98 back to line conductor 92. By reason of this latter maintaining circuit relay 80 will not be deenergized until the temperature has risen to a value above 72 at which blade 16 will separate from contact 18 interrupting the maintaining circuit thus providing for a xed operating differential at the thermostat. When blade 83` engages its associated contact the coil 4G of relay |0 becomes energized through the following circuit (it being recalled that unit 54 is not in use but that screws are in place as seenin outline in Figure 2): from line conductor 93 through wire 94, coil 46, wire 49 (see Figure 2), contact strip 40, the head of the screw on the right, contact strip 2|, wire 5|, wire 00, switch blade 83, contact 85, and wire back to line conductor |92. The circuit energizing the other relay coil 41 is as follows: from line conductor 93 to wire 94, wire 48 (see Figure 2), contact strip 38, the head of the screw on the left, contact strip 39, wire 50,' coil 41, wire |00, switch blade 83, contact 85, and wire |0| back to line conductor 92. From the foregoing circuits it is apparent that the coils 46 and 41 are now connected in parallel and by reason of their energization the armature |4 of relay l0 is rotated in a counter-clockwise direction bringing load contacts and 26 into engagement with each other which energizes the motor 9| through the following circuit: from line conductor 93 to wire |02, contact 25, contact 26, wire |03, resistance 90, wire |04, motor 9|, and wire |05 back to line conductor 92. Motor 9| will remain energized until blade 16 of thermostat disengages from contact 18 as described.

From the above it is to be noted that the wire 95 which forms part of the original energizing circuit for relay 80 as well as the maintaining circuit for relay 80 is connected to the left end of coil 41 and thus line voltage is available for impression on the relay 80 as is apparent from the said circuits.

In the circuit arrangement of Figure 1 the contacts 29 and 30 are not used. In this particular figure the arrangement is one wherein the relay l0 is relatively large and the pilot relay 80 is employed sothat the operating current for the relatively large relay |0 will not have to be carried by the contacts of the thermostat 14. The maintaining circuit controlled by the thermostat is established by the switch blade 82 of the pilot relay 80. When smaller relays corresponding to the relay I0 are used it is not necessary to use the pilot relay 80 and under these circumstances the contacts 29 and 30 serve to establish they maintaining circuit controlled by blade 16 on the thermostat. When the pilot relay 80 is not to be used Wire 95 would be omitted and wire |00 would be connected to contact 18. Wire 96 would be connected directly to line conductor 92. Also Wire 99 would connect to contact 29 and contact 30 would be connected to line conductor 92. The pilot relay being omitted the switch of the overload cut-out 86 would be connected in series with wire |00. The operation of the arrangement just described would be similar to the operation with the pilot relay with the function of the pilot relay of course omitted.

Assume now that the line cionductors 92 and 98 are connected to a source of alternating current power of 220` volts at a frequency of cycles. Under these circumstances only one screw will be inserted in the block 31 and that in the opening 45 so as to bridge the contact strips 39 and 40. Upon a demand for motor operation by the thermostat 14 the pilot relay 80 will now be energized through the following circuit: from line conductor 93 through wire 94, coil 46, wire 49 (see Figure 2), contact strip 40, the head of the` screw, contact strip 39, wire 50, wire 95, contact 18, thermostat blade 16, thermostat blade 11, contact 19, wire 96, coil 8|, wire 91, overload cut-out 86, and wire 98 back to line conductor 92. As soon as coil 8| is energized switch blades 32 and 83 move to the left into engagement with their respective contacts, engagement of blade 82 with contact 84 completing a maintaining circuit for coil 8| as follows: from line conductor 93 through wire 94, coil 46, wire 49 (see Figure 2), contact strip 40, the head of the screw, contact strip 39, wire 50, wire 95, contact 18, thermostat blade 16, element 15, wire 99, contact 84, switch blade 82, wire |02, coil 8|, wire 91, overload cut-out 88, and wire 98 back to line conductor 92. Engagement of switch blade 83 with contact 85 energizes the relay l0 as follows, the coils 46 and 41 now being connected in series: from line conductor 93 through wire 94, coil 46, wire 49 (see Figure 2), contact strip 40, the head of the screw, contact strip 39, wire 50, coil 41, wire |00, switch blade 83, contact 85, and wire |0| back to line conductor 92. Energization of relay |0 again causes counter-clockwise rotation` of armature I4 moving contacts 25 and 26 into engagement causing venergization of motor 9| through the same circuit as was described above.

It will be noted from the foregoing that when line conductors 92 and 93 are connected to 220 volt power that both theoriginal and the maintaining circuit for energizing relay 80 are connected across the coil 46 of relay |0. As the two coils 46 and 41 are now in series the voltage drop across each one will be substantially volts. Therefore the voltage impressed on relay 80 will be 110 volts even though the voltage of the power source is 220 volts. It is obvious 'therefore that by reason of my particular way of interconnecting the pilot relay I need provide no means for adapting'the pilot relay to voltages other than 110 even though I change the Wiring of the main relay I0 when different voltages are to-be employed. This manner of employing the pilot relay forms an important feature of my invention.

I will now describe the manner of using my 1 relay with direct current power sources and alternating current power sources having frequencies of other than 60 cycles. Witn such power sources I employ the adaptor unit 54 and for 110 volts direct current or for 110 volts alternating current at frequencies of 25 or 40 cycles, for example, I employ the adaptor unit 54 in the position in which it is shown in Figure 1. The system of Figure 1 now operates in the same manner as described above for 110 volts alternating current at 60 cycles except that coils 46 and 41 are now in parallel but with a resistance in series with each coil. Also a resistance is placed in series with coil 8| of pilot relay 80. As I have pointed out above a coil which may operate properly at 110 volts alternating current Will overheat when 110 volts direct current is impressed on the coil unless a resistance is placed in series with the coil. Similarly if a coil operates properly at 110 volts alternating current at 60 cycles, at a lower frequency even though the voltage be the saine a resistance cut-out 86, and wire 98 back to line conductor should be placed in series with the coil to pre- 92. Engagement of blade 83 with contact 85 vent overheating. Having' the foregoing in mind, completes a circuit through the coils' 46 and 41 when thermostatv 14 now indicates a demand for and resistances 68 and 69 as follows: from line burner operation the circuit for energizing re- 5 conductor 93 through wire 94, coil 46, wire 4.9 lay 80 is as follows: from line conductor 93 (see Figure 2), Contact Strip 40, Contact Strip through wire 94, wire 48, contact strip 38, con- 60, connection 1|, contact strip 58, resistance tact strip 55, resistance 68, contact strip 56, 69, contact strip 51, the head of the screw, contact strip 39, wire 5|), wire 95; contact 18, Contact strip 56, rsistance 68, contact strip 55, thermostat blade 16, thermostat blade 11, con-` connection 10, contact strip 59, contact strip 39, tact 19, wire 96, coil 8|, wire 91, overload cutwire 50, coil 41, wire |00, blade 83, contact 85, out 86, and wire 98 back to line conductor 92. and wire ||J| back to the line conductor 92. Enimmediately upon energization of coil 8| switch ergiZatiOn 0f relay l0 again Causes Operation 0f blades 82 and 83 are again moved to the left motor 9| in the manner already described. From into engagement with .their respective contacts, the foregoing it is t0 be Seen that both resistanees blade 82 establishing a maintainingcilcuit as 68 and 69 are in series with the two coils 46 follows: from line conductor 93 to wire 94, wire and 41 also in' series. It lslllonted Out that When 48, contact strip 38, contact strip 55, resistance 110 volts direct current or 110 volts alternating 68, contact strip 56, contact strip 39, wire 50, current at a frequency lower than 60 is supplied wire 95, contact 18, thermostat blade 16, thermothat a resistance is placed in the circuit of the static element 15, wire 99, contact 84, switch pilot relay coil 8| and if this type 0f direct e111'- blade 82, wire |02, coil 8|, wire 91, overload cutrent or alternating current power is supplied out 86, and wire 98 back to line conductor 92. at 220 volts an additional resistance as well is Engagement of blade 83 with contact 85 enerplaced in circuit with the coil 8| of the pilot gizes coils 46 and 41 through parallel circuits, 25 relay. the eircuit'for coil 46 being as follows: from The problems solved by the present invention line conductor 93 through wire 94, coil 46, wire will be' understood by those skilled in the art 49, contact strip 40, contact strip 51, resistance and the novel and unique manner in Whh they 69, contact strip 58, contact strip 4|, wire 51,' have been met so as to render the inventive dewire |00, blade 83, contact 85, and wire |01 30 vice very flexible as regardsits adaptability to back to line conductor 92. The parallel circuit various power sources will be appreciated. Frefor coil 41 is as follows: from line conductor 93 elllently the relay and associated adapter unit, through'wire 94, wire 48, contact strip 38, conthe overload cut-out and the pilot relay of Figtact strip 55, resistance 68, contact strip 56, ure 1 Will be @Omblned in a Single COInPaCt houscontact strip 39, wire 5u, coil 41, wire loo, blade 35 ins or casing and marketed as a unit. Obvi- 83, contact 85 and wire 10i back to line oonously by reason of the various coils and resist-v ductor 92. Energization'of the two coils of r, ences the amount of heating of each must be relay |0 now operates that relay in a manner reduced as much as possible in order to preclude corresponding to that already described for energizing the motor 9|.

For adapting the relay now to direct current voltages of 220ivolts or to alternating current voltages at frequencies below 60 cycles of 25 or ment Costs and aCilltatins distribution by PIO- cycles, for example, the unit 5c is removed, viding considerably more flexible and more uniinverted and placed in the block 31 with a single 45 Versally adaptable apparatusscrew to retain it in position in the manner Figure 3 of the drawings represents a InOdifishown in outline in Figure 2 with the head of cation of my invention wherein I employ a difthe screw bridging the contact strips 56 and 51, ferent form of adaptor unit but wherein the re- Contact strips 59 and 6o will now be mating ley itself iS the seme es the relay of Figure l with contact strips 39 and 40 Kof the block 31, 50 except that the armature I4 carries an addi- The circuit for energizing the relay coil sl now tional member 3W forming an operating finger includes in series both the resistances 68 and i which cooperates with the adaptor unit of this 69 as well as the coil 46. The circuit for enerfigure in a manner Which Will be described. The gizing coil 8| will now be as follows: from line Contact strips 33 t0 4l 0f Figure 3 Can be bridged conductor 93 through wire 94, coil 46, wire 49 55 by inserting screws in the openings between them (see Figure 2), contact strip 4'0, contact strip 60, connection 1|, contact strip 59, resistance 69, contact strip 51, the head of the screw, con- ,40 the limit established by underwriters standards. The present invention presents satisfactory ways and means of reducing production and developdescribed in connection therewith. As has been pointed out, the screws are used for effecting tact strip 56, resistance 68, contact strip 55, either a series or parallel connection between connection 10, contact strip 59, contact strip the COllS When the relay is used With alternating 3s, wire 5u, wire 95, contact 1 8, blade 16, blade current power- When using the relay with di- 11 of thermostat 14, contact 19, wire 96, coil 8|, wire 91, overload cut-out s6, and wire sa back current the amount of' current now which is to line conductor 92. Eeergization of coil al necessary to cause the relay to pull in 1s vmore again moves blades s2 'and 83 izo-trie left blade 65 than enough to hold the relay in its in position 82 completing a maintaining circuit as follows: t and Will Cause Overheating 0f the COlS unless from line co-lduc tor 93, wire 94, coil 46, wire 49 the current flow is reduced after the relay has (see Figure 2), contact strip 4u, contact strip been pulled in. 'The adaptor unit 354 of Figure 60, connection 1|, contact strip 58, resistance v 69, contact strip 51, the head of the screw, con- "0 large current flow will take `place through the the temperature from rising to a value exceeding in the same manner as shown in Figure 2 and rect current or very low frequency alternating' 3 is therefore constructed` so that a relatively s tact strip 56, resistance 68, contact strip 55, coils for causing the relay t0 pull ln and the connection `10, contact strip 59, contact strip 39, amount of current flow will be automatically rewire 50, wire 95, contact 18, thermostat blade 16, duced as soon as the relay has been pulled ln thermostatic element 15, wire 99, contact 84, so as to prevent any overheating of the coils.`

blade 82, wire |02, coil 8|, wire 91, overload 75 The adaptor unit 354 is constructed similarly to that of Figures 1 and 2 but it will be seen that it has an integral right'hand portion 311 which forms a housing for mechanism which I am about to describe. Numerals 312 and 313 represent a pair of similar resistances which are suitably mounted within the portion 31 I. -The adjacent end terminals 323 and 324 of the two resistances 312 and 313 form electrical contacts with which cooperate flexible switch blades 314 and 315. The blades 314 and 315 have an angular shape as shown, each having a portion attached to an intermediate point on its respective resistance and a longer part which is normally in engagement with the end terminal of its respective resistance. When the switch blades 314 and 315 are in the position shown on Figure 3 they serve to shunt that portion of their respective resistances which they bridge. Engaging the free ends of both switch blades 314 and 315 is the end of a plunger 316 which extends through a side wall of the portion 311 of the adaptor unit. The protruding end of the plunger 316 is so arranged that it is engaged by the operating ringer 319 of the relay when the armature 14 moves in a' counter-clockwise direction so that the plunger is pushed to the left separating the switch blades 314 and 315 from the end terminals of their associated resistances. Theelectrical connections within the adaptor unit 354 may, as in the pre- Vious embodiment, be in the form of Wires or metal strips. In the present embodiment of the invention the ends of resistance 312 are connected to contact strips 55 and 56 by connections 31'1 and 318. Contact strip 59 is connected to connection 311 by a connection 319 and contact strip 60 is connected to contactI strip 58 by a connection 320. One end of resistance 313 is connected to contact strip 5`1 by a connection 321 and the other end of resistance 313 is connected to connection 320 (leading to contact strip 58) by a connection 322. The unit 354 may be attached to the block 3'1 by means of a screw 63 in the same manner as the adaptor unit is attached as shown in Figure 1. 'I'he adaptor unit 354 is substantially symmetrical about a tranverse horizontal axis passing through the axis of the plunger 316. The adaptor unit 354 is therefore invertible in the same manner as the adaptor unit of Figures 1 and 2, the projection 61 extending into the small recess 42 when the unit is inverted. Due to the fact that the plunger 316 has an axis coinciding with the axis of symmetry, when the adaptor unit is inverted the plunger is in the same relative position as it was before with respect to the operating finger 310. Therefore when the adaptor unit is-inverted the relay armature. operates the plunger 316 in exactly the same manner.

The relay of Figure 3 may be connected in a system the same as the one shown in Figure 1 either in combination with a pilot relay or having a thermostat or similar instrument directly controlling the relay 10. That is, the wire 94 of Figure 3 would be connected to one side of tlie line and the wire 100 of Figure 3 would be connectible to the other side of the line either through the pilot relay or directly through the.

thermostatic contacts. By comparing the adaptor unit 354 and the adaptor unit of Figures 1 and 2 it can be seen that the electrical connections of the units themselves in thetwo emin Figure 3 the relay coils 46 and 41 are Connected in parallel with part of each of the resistances 312 and 313 in series with each coil. Upon energization of the relay 11i-in a manner similar to that described in connection with the previous embodiment the electrical circuit for coil 46 is as follows: from wire 94 through coil 46, wire 49, contact strip 40, contact strip 51, connection 321, terminal 324, switch blade 315, part of resistance 313, connection 322, part of connection 320, contact strip 58, contact strip 41, wire 51 to wire 1110, it being understood as pointed out above that wire 94 is connected to one side of the line and wire 100 is connectible to the other side of the line either through a pilot relay or thermostatic contacts as in the previous embodiment. The cincuit through coil 4'1 is as follows: from wire 94 through wire 48, contact strip 38, contact strip 55, connection 311, part of resistance 312, switch blade 314, terminal 323, connection 318, contact strip 56, contact strip 39, wire 50, coil 4l back to wire 100. As soon as the relay armature 14 moves to in position upon energization of the coils operating finger 310 pushes plunger 316 to the left moving switch blades 314 and 315 away from the terminals 323 and 324. Upon this occurring the shunts established by the switch blades are interrupted and the circuit o f each of the coils 413 and 41 now will include that part of the resistances 312 and 313 which was' shunted by their associated switch blades. Obviously therefore there-was less resistance in the circuit of each coil upon initial energization of the relay permitting a relatively large current iiow for causing the relay to be moved to in position and upon the relay armature reaching its in position bodiments' are the same, the difference between Y the units being the switches which cooperate with two resistances 312 and 313.

With theadaptor unit 354 in the position shown operation of the plunger 316 caused additional resistance to be placed in the circuit of each coil. This additional resistance reduces the current :dow and prevents excess heating of the coils.

By inverting the unit 354 in the same manner as the adaptor unit of Figures 1 and 2 the coils 46 and 4l may be connected in series with each other and 'with resistances 312 and 313, the plunger 316 operating in the saine manner to add a part of each resistance to the series circuit upon pulling in of the relay. When the unit 354 is inverted a single screw is used to retain it in in position and to bridge the contact strips 56 and 51 in the same manner as may be seen in the upper part of Figure l.` The series circuit through the coils and resistances when the unit 354 is'inverted is as follows: from wire 94 through coilv 46, wire 49, contact strip 40, contact strip 60, connection 320, connection 322, part of resistance 313, switch blade 315, terminal 324, connection 321, contact strip 57, the head of the screw bridging contact strips 51 and 56, contact strip 56, connection 318, terminal 323, switch blade 314, part of resistance 312, connection 31'1, connection 319, contact strip 59, contact strip 39, wire 511, coil 41 back to wire 100. As soon as the relay 111 is energized upon completion of this circuit the armature 14 moves in a counterclockwise direction pushing plunger 316 to the left and interrupting the shunts established by switch blades 314 and 315 and adding the shunted portions of resistances 312 and 31-3 to the series circuit. The unit 354 would be in an inverted position for 220 volt operation as described in connection with previous embodiments and as valready described the additional resistance placed y already pointed out,

vthe end of the upper leg my invention wherein I have shown improvements in changing over the relay for use with direct current or very low frequency alternating current. The relay I of Figure 4 is the same as the relay of Figure 1 with the exception that the armature member does not have the brass band 2| encircling its extremity. As I have this brass band is more necessary when using direct current than when using alternating current. I have therefore provided an arrangement whereby a brass element is interposed between the core |2 and armature member l5 only when direct current or very low frequency alternating current is used with the relay, the brass element being part of the adaptor unit which is attached to the relay when direct current or very low frequency alternating current is to be used. The adaptor unit 454 of Figure 4 is constructed similarly to the adaptor unit of Figure 3, also having a portion 4|! forming a housing for resistances` 4|2 and 4|3 disposed therein. The unit 454 has only four contact strips to 58 coresponding to similarly' numbered contact strips of previous embodiments it not being intended that this unit be inverted. The unit 454 is heid in place in the block 31 by means of a screw 463. The plunger 4|6 of the present embodiment operates the switch blades 4|4 and 4|5 in a manner similar to that of the embodiment of Figure 3 but the mechanism for operating the plunger is slightly modifled. Integral with the unit 454 is a lug 430 to which is pivoted an operating lever 43|, the upper end of which operatively engages the end of the plunger 4|6 which protrudes through the housing portion 4||. The lower end of lever 43| extends to a pointadjacent the upper leg of the core |2 and fastened to this end of the lever 43| is a small brass strip or plate 432 which normally takes a position in the path of movement of the armature member |5 when the armature is moved in a counter-clockwise direction. When the relay of Figure 4 is energized and the armature moved in a counter-clockwise direction the armature'mernber |5 engages thebrass element 432 rotating lever 43| in a clockwise direction and moving element 432 into contact with of the core |2. Clockwise movement of lever 43| moves plunger 4|6 to the right separating switch blades 4|4 and 4|5 from their associated terminals 423 and 424, this operation corresponding to that of the ernbodiment of Figure 3. The brass strip element 432 serves the same purpose as the brass ring 2| of Figure l. The resistances 4|2 and 4|3 are connected between the contact strips 55 to 56 in the same way as the corresponding resistances of the adaptor unit 354 of Figure 3. The coils 46 and 41 .are connected in parallel when the adaptor unit 454 is in place and the circuits through the coils when the relay is energized are the same as the circuits through the coils of Figure 3 when the adaptor unit 354 of that figure is in the position in which it is shown. Therefore it is not necessary thatrthese circuits be traced again, the operation of the switch blades associated with resistances being substantially the same.

In Figure 5 I have shown a detail portionof a relay which relay is constructed exactly the same as the relay I0 of Figure 3.- InFigure 5'I have shown a still further form of adaptor unit, the particular purpose of which is to enable adjustments to be made of the amount of resistance which is added to the coil circuit or circuits for 7'5 the resistance 535 are connected to the contact directing current operation. The adaptor unit 554 of Figure. 5 is constructed somewhat similarly to the unit of Figure 1 with respect to the resistances and similarly to the unit of Figure 3 with respect to invertibility. In addition to the resistances 68 and 69 the unit 554 has a resistance 535 connected between the contact strips 56 and 51. In addition to the opening 62 extending through the unit for receiving a screw the unit has two additional openings 536 and 531 extending through the unit between contact strips 55 and 56 and between the contact strips 51 and 58 for retaining the unit in place and for bridging the contact strips adjacent to the openings. In addition to the projection 6| corresponding to that of previous embodiments the unit 554 has in addition a corresponding projection 56| on the opposite side of the unit which has the same purpose of vpreventing the retaining screw from bridging the contact strips adjacent to the projection. The unit 554 has a housing portion 5|| similar to that of Figure 3 but encloses instead of resistances, a switch comprising a contact 538 and a flexible switch blade 539. A plunger 5|6 cooperates with the switch blade 539 and extends through a side wall of the housing 5||. The plunger 5|6 is operated by an operating iinger 5|0 associated with the relay in the same/manner as the plunger of Figure 3 is operated, the switch within the housing 5|| being opened when the relay is energized. Contact strips 55 and 59 are joined by a connection 510 and contact strips 58 and 60 are joined by a connection 51|. 'I'he contact strips 56 and 51 and therefore the ends of 536 and the switch blade 539. byconnections 540 and 54|, respectively. The axis of plunger 5|6 coincides with an axis of symmetry of the unit 554. Corresponding to the description of the unit 354 of Figure 3, theunit 554 may therefore be inverted and the plunger 5|6 will be in exactly the same relative position with respect to the operating nnger 5|0 when it is inverted so that the plunger 5|6 is operated in the same manner in both positions.

With'the unit 554 in the position shown the coils are connected for series operation. The unit may be retained in this position by two screws if desired, the outlines of which are shown on Figure 5. Whentwo screws aroused in the manner shown none of the resistors within the adaptor unit are in circuit with the coils when the relay is energized and before the armature v has been pulled in. The circuit for the coils is as follows: from wire 94 through coil 46, wire 49, contact strip 40, contact strip 60; connection 51|, contact strip 58, the head of the screw bridging contact strips 51 and 58, contact strip 51, connection 540, contact 538, switch blade' 539, connection tu, Contact strip 5s, the head of the screw bridging contact strips v55 and 56, contact strip 55, connection 510, contact strip 59, contact strip 39, wire 50, and coil 41 back to Wire |00. is soon as the relay is energized by this circuit and the armature is moved in a counter-clockwise direction so as to operatethe plunger 5|6 switch blade 539 is moved away from contact 536 so that the series circuit no longer extends through the switch within housing 5|| butl instead is as follows: from wire 94 through coil 46, wire 49, contact strip 40, contact strip 60, connection 51|, contact strip 56, the head of `the screw bridging contact strips 51 and 56, contact strip 51, resistance 535, contact strip 56, the head of the screw bridging contact strips 55 and 5l,

contact strip 55, connection 510, contact strip 59, contact strip 39, wire 50, and coil 41 back to wire I D0.

From the foregoing it is seen that the opening of the switch within housing l l has caused resistance 535 to be placed in series circuit relationship with the coils so as to reduce the current flow for the purpose already described in connection with previous embodiments. If it is desired to still further reduce the amount of current passing through the coils 46 and 41 when the unit 554 is in use either or both of the two screws shown in outline can be removedand a-single retaining screw inserted through the opening 62. For example, if the screw bridging contact strips y 51 and 58 is removed the above described circuit instead of extending through the head of this screw would instead have to pass through the resistance 69 connected between contact strips 51 and 58. Similarly if the screw bridging contact strips 55 and\56 were removed the above described circuit instead of passing through the head of this screw would have to extend through resistances 68 connecting contact strips 55 and 55,. In this manner the operating current for the coils may be suitably adjusted when the unit 554 is in place for use with direct current or with alternating current at relatively lower frequencies.

When the unit 554 is inverted it is retained in position by a screw passing through the opening 62, the projection 6| preventing the head of the screw from bridging the contact strips 5S and 6U the unit now taking the position corresponding to the position of the unit 54 as, seen in Figure 1. In inverted position of the unit 554 the coils 45 and 41 are connected in parallel with the resistance 68 in series with coil 46 and resistance 69 in series with coil 41. These circuits correspond to circuits previously traced in connection with the description of other embodiments and need not be traced again. When the unit 554 is in inverted position it is to be seen that there is also a series connection between the coils 4B and 41 provided by the switch within the housing 5H when the relay is out and provided by the resistance 535 when the relay is in its in position. However the parallel circuit paths are of less resistance than the series circuit path through the coils and inasmuch as electrical current will always follow the path of least resistance the series connection does not disturb the-proper functioning of the apparatus as intended to be broughtv about by the parallel connection of the coils.

The disclosed embodiments of my invention are illustrative of varied forms and aspects which it may take. The invention is not to be restricted to the specic forms of construction and arrangements which have been disclosed inasmuch as it is apparent that the apparatus, particularly the adaptor units may be somewhat differently formed and constructedl by those skilled in the art without departing from the invention. The boundaries of my invention are to be determined in accordance with the scope of the appended claims.

I claim as my invention:

1. In a relay, in combination, a pair of coils adapted to be connected to a source of power supply, contacts connected to said coils and adjustable means for bridging said contacts whereby said coils may be connected either in series or in parallel, said means ycomprising a removable unit having contacts for engaging said aforementioned ,contacts and screws insertable through lio said unit for retaining said unit in position, said unit having contacts bridgable by said retaining screws, said unit embodying resistances which become connected in predetermined circuit relationship with said coils when said unit is in Aposition.

2. As an article of manufacture a relay comprising in combination, a pair of coils, a source of power for said coils, contact members connected to said coils, said members being arranged adjacent each other whereby adjacent members may be bridged, said coils becoming connected in series or in parallel depending upon which members are bridged, and a unit having contacts spacedly arrangedso that said unit may be placed in a position with its contacts engaging said contact members, said unit having resistances connected between its contacts whereby when the unit is in position said resistances are in circuit with said coils.

3. As an article of manufacture a relay comprising in combination a -pair of coils, a source of power for said coils, contact members connected to said coils, said members being arranged adjacent each other whereby adjacent members may be bridged, said coils becoming connected in series or in parallel depending upon which members are bridged, a unit having a plurality of contacts spacedly arranged. so that said unit may be placed in a position with some of its contacts engaging said contact members, means for bridging other of said contacts, said unit having connections including resistances between its contacts whereby when the unit is in position said resistances are in circuit with said coils according to a relationship depending on which of said contacts are bridged.

4. As an article of manufacture a relay comprising in combination a pair of coils, a source of power for said coils, contact members connected to said coils, said members being arranged adjacent each other whereby adjacent members may be bridged, 'said coils becoming connected in series or in parallel depending upon which members are bridged, a unit having a plurality of contacts spacedly arranged so that said unit may be placed in a position with some of its contacts engaging said contact members, means for bridging other of the contacts of said unit, said unit having connections including resistances between its contacts, said unit, bridging means, and said contact members being mutually cooperable whereby said coils may be connected in series relationship including at least one of said resistances or in parallel relationship with at least one coil having a resistance in series therewith.

5. As an article of manufacture a relayv cornprising in combination, a pair of coils, a source of power for said coils, contact members connected to said coils, said members being arranged adjacent each other whereby adjacent members may be bridged, said coils becoming connected in series or in parallel depending upon which members aref bridged, a unit having a plurality of contacts spacedly arranged so that said unit may be placed in a position with some of its contacts engaging said contact members, means for bridging other of the contacts of said unit, said unit having connections includingresistances between its contacts, said unit including a switch connected in shunt relation with a resistance, means whereby said switch may be actuated by said relay when said unit is in position, said unit, bridging means, and contact members being mutually c0- operable whereby said coils may be connected in series relationship including at least one ofssaid relay when said resistances or in parallel relationship with at least one coil having a resistance in series therewith and saidswitch interrupting the aforementioned shunt connection upon operation of the relay.

6. As an article of manufacture a relaycomprising in combination, a pair of coils, a source of power for said coils, -contact members connected to said coils, said members being arranged adjacent each other whereby adjacent mem ers may be bridged, said coils becoming connected in series or in parallel depending upon which members are bridged, a unit having contacts spacedly arranged so that said unit may be placed in a position with its contacts engaging said contact members, said unit` having other contacts and connections including resistances between its contacts, means for bridging said other contacts whereby when said unit is in position said coils are connected in series with each other and with at least one resistance.

7. As an article of manufacture a relay comprising in combination, a pair of coils, a source of power for said coils, contact members connected to saidcoils, said members beingf arranged adjacent eachother whereby adjacent members may be bridged, said coils becoming connected in series or in parallel depending upon which members are bridged, a unit having contacts spacedly arranged so that said unit may be placed in a position with its contacts engaging said contact members, said unit having other contacts, connections includingA resistances between its contacts,l and a switch connected in shunt relationship with a resistance, means whereby said relay may operate said switch, means for bridging said other contacts whereby when said unit is in position, said coils are connected in series with each other and withthe resistance with which said switch is connected in shunt relationship and said switch interrupting said shunt connection upon operation of the relay.

8. As an article of manufacture a relay comprising in combination, a pair of coils, a source' of power for said coils, contact members connected to said '.coils, said members being arranged adjacent each other whereby adjacent members may be bridged, said coils becoming connected in series or' in parallel depending upon whichv members are bridged, an adaptor unit having a plurality of spacedly arranged contacts' arranged so that said unit may be .placed-in a plurality of positions in each of which someoi its contacts' engage said contact members, said unit having connections including a resistance between its contacts whereby said coils become connected when said unit is in position, said unit embodying switch means connected in shunt relationship with said resistance, said unit being so constructed and structurally related to said relay that said switch means is engaged and operated by said y unit is in any one of a plurality of positions, said shunt connection becoming interrupted upon operation of the relay.

9. As an article of manufacture, in combination, a relay having windings and an armature, means comprising an adaptor Aunit cooperable with said relay and detachable fromsaidrelay.

said unit embodying switch means and being attachable to said relay in a. plurality of different positions, said unit being so constructed and structurally related to said ^relay that in a plurality of its positions said switch means is in position to be engaged and operated by said armature.

10. As an tion, a relay having windings and an armature, means comprising an adaptor unit cooperable with said relay for adapting it to various different power sources by connecting said windings in diierent .circuit relationships, said means including contact members and said unit having a plurality of contacts and being attachable to said relay in a plurality of vpositions with contacts. engaging said contact members, said contacts having connections including a resistance therebetween whereby the circuit relationship between said coils depends on the position of the unit, said `unit having switch means connected in shunt relationship with said resistance, said unit being so constructed and arranged that in a plurality of its positions said switch means is in the same relative position with respect to said armature whereby it can be engaged and actuated thereby.

11. As an article of manufacture a relay comy prising in combination, two coils, means comprising contact members connected to said coils, said contact members being so arranged 'that different members may be bridged, means comprising a detachable adaptor unit capableof being attached to said relay for bridging said contact members, said unit embodying a resistance and contacts capable of being connected for eiecting various circuit relationships between said coils and resistance.

12. In apparatus of the character described,'in

combination, a main relay having windings and an armature, means cooperable with said windings for adapting said main relay to various dif'- ferent power lsources by connecting said `wind ings in various different circuit relationships, a

' able unitv having pilot relay cooperating with said main relay, said pilot relay being so interconnected to said main relay that the voltage impressed on said pilot relay is substantially the same circuit relationship of said windings is changed for power sources of different voltage whereby said pilot relay need not be adaptable to' different voltages.

13. In a relay in combnation, two windings, an Iarmature cooperating with said windings, a source of power for said relay, said armature being movable to an in position upon energization of the relay and being movable to an out position upon deenergization of the relay, nected to said windings and arranged adjacent each other, means comprising screws insertable between said contact members for bridging adjacent contact members, the arrangement being such that said contact members can be bridged for connecting said coils either in series or parallel circuit relationship.

14. As an article of manufacture in combination, a relay having windings, and an armature, means forming electrical contacts connected to saidwindings, and means comprising an adjustcontact members adapted to engage with said contacts, said unit embodying an electrical resistance and switch-means connected in circuit relationship with said contact members, said unit being adjustable rto various f positions "wherein its contact members engage with said contacts and said unit beingso constructed and arranged that in a plurality of its positions said switchA means is in a relative position so asto be actuable by said armature.

15. As an article of manufacture, in combination, a relay having windings and an armature means, means comprising an adjustably mounted article of manufacture, in combinaeven though the contact members conunit cooperating with said relay, bodying switch means adapted to said armature means, said unit structed and structurally related said unit embe actuated by beingso consaid armature.

16. In apparatus of the character described,

means able therewith whereby different of said unit' terminals may cooperate with dlilerent panel terminals for effecting various circuit connection relationships between the various terminals, said arranged that when the devices are connected in series. 17. As an article of manufacture, means forming a panel having a plurality of electrical terminals, means comprising aunlt cooperable with said panel having terminals adapted to engage and contact with said iirst mentioned terminals, said unit having connections between certain of its terminals and switch means forming part of and mutually cooperable there-v said unit terminals may cooperate with different panel terminals for circuit connection relationships between the various terminals, and means forming a relay having amature means adapted to said unit being adjustable relav actuate said switch means, said unit being so constructed and arranged that in a plurality of positions said switch means is in a relative position wherein the switch means can be actuated by said armature means.

18. In 'apparatus of the character described, means forming a panel having a plurality of spaced electrical contact members, means connecting said member to electric current carrying devices, means comprising a unit cooperable with said panel and having a plurality of spaced contact members adapted to cooperate with said iirst mentioned contact members, said unit having means forming connections between its contact members, said unit being adjustable to various positions relative to said panel and being mutually cooperable therewith whereby different of said unit contact members may cooperate with diilerent panel contact members for eiecting various circuit relationships between the panel contact members through the said connection forming means of the unit, said unit contact members being so arranged that in one position of the unit said devices are connected in parallel and in another position said devices are connected in series.

19. As an article oi' manufacture, means form lng a panel having a plurality of electrical terminals, means comprising a unit cooperable with said panel having terminals adaptedvto engage and contact with said first mentioned terminals, said unit embodying resistance means connected between certain of its terminals and being adjustable relative to said panel and mutually cooperable therewith whereby diiferent of said unit terminals may cooperate with different panel terminals for eiIecting various circuit connection relationships between the various terminals, and means for bridging certain of said unit terminals,

ALWIN B. NEWTON. 

